This disclosure relates generally to surgical navigation and more particularly to a magnetic tracker system and method for use for surgical navigation utilizing an excitation scheme using a plurality of frequencies.
Surgical navigation systems (SNS) frequently track the precise position and orientation of surgical instruments (e.g., catheters), implants or other medical devices, conventionally, in relation to multidimensional images of an anatomy of a patient using a tracker system. Additionally, SNS includes visualization tools to provide the surgeon with co-registered views of these surgical instruments, implants or other medical devices within the region of interest.
The multidimensional images may be generated either prior to or during the surgical procedure. For example, any suitable medical imaging technique, such as an X-ray, computed tomography (CT), magnetic resonance (MR), positron emission tomography (PET), ultrasound, or any other suitable imaging technique, as well as any combinations thereof may be utilized. After registering the multidimensional images to the position and orientation of the patient, or to the position and orientation of an anatomical feature or region of interest, the combination of the multidimensional images with graphical representations of the navigated surgical instruments, implants or other medical devices provides position and orientation information that allows a medical practitioner to manipulate the surgical instruments, implants or other medical devices to desired positions and orientations.
Conventional SNS include tracker systems that use position and orientation sensors, or sensing sub-systems based on, for example, electromagnetic (EM), radio frequency (RF), optical (line-of-sight), and/or mechanical technology.
EM sensors are typically implemented with coils or microcoils to generate and detect the magnetic fields. While coil based EM sensors have been successfully implemented, they may be susceptible to magnetic field distortions that arise from eddy currents in nearby conducting objects, such as, metal objects surrounding the patient. The tracking technique used with coil based EM sensors relies on a stable magnetic field, or a known magnetic field map. Therefore, unpredictable disturbances resulting from metallic objects in the magnetic field reduce the accuracy or may even render the tracking technique useless without additional position measurements, such as, from a medical image (e.g., CT, MR, PET). Therefore, there is a need for a tracker system to minimize or remove magnetic field distortions without reducing sensitivity of the EM sensors.